An overview of NMR-based metabolomics to identify secondary plant compounds involved in host plant resistance

Secondary metabolites provide a potential source for the generation of host plant resistance and development of biopesticides. This is especially important in view of the rapid and vast spread of agricultural and horticultural pests worldwide. Multiple pests control tactics in the framework of an integrated pest management (IPM) programme are necessary. One important strategy of IPM is the use of chemical host plant resistance. Up to now the study of chemical host plant resistance has, for technical reasons, been restricted to the identification of single compounds applying specific chemical analyses adapted to the compound in question. In biological processes however, usually more than one compound is involved. Metabolomics allows the simultaneous detection of a wide range of compounds, providing an immediate image of the metabolome of a plant. One of the most universally used metabolomic approaches comprises nuclear magnetic resonance spectroscopy (NMR). It has been NMR which has been applied as a proof of principle to show that metabolomics can constitute a major advancement in the study of host plant resistance. Here we give an overview on the application of NMR to identify candidate compounds for host plant resistance. We focus on host plant resistance to western flower thrips (Frankliniella occidentalis) which has been used as a model for different plant species

Controle de mosca-branca com extratos vegetais, em tomateiro cultivado em casa-de-vegetação Use of plant extracts on whitefly control in tomato grown in greenhouse

Visando buscar métodos alternativos no controle da mosca-branca Bemisia tabaci (Gennadius) biótipo B em tomateiro, foram realizados testes de atratividade e preferência para oviposição em casa-de-vegetação, utilizando-se quatorze extratos aquosos a 3% (peso/volume). Os extratos foram preparados com partes de Azadirachta indica, Trichilia pallida,Chenopodium ambrosioides,Piper nigrum,Melia azedarach,Ruta graveolens,Ricinus communis,Mentha pulegium,Tagetes erecta,Eucalyptus citriodora,Cymbopogon nardus e Coriandrum sativum. Numa segunda etapa, os extratos mais eficientes em casa-de-vegetação foram observados em laboratório, a fim de avaliar o possível efeito sistêmico dos mesmos sobre ninfas da mosca-branca. Constatou-se que as plantas de tomateiro pulverizadas com extratos à base de folhas de M. pulegium e folhas e sementes de A. indica foram menos atrativas aos adultos do inseto. Plantas pulverizadas com extratos de folhas de A. indica e folhas + ramos de R. communis mostraram efeitos deterrentes à oviposição do inseto, reduzindo o número de ovos; em contrapartida, o extrato à base de folhas de C. nardus estimulou a oviposição da mosca-branca sobre as plantas. O uso dos extratos por via sistêmica não afetou o período de desenvolvimento (ovo-adulto) da mosca-branca; entretanto, a presença de extratos de sementes e folhas de A. indica e de folhas de M. pulegium provocou aumento significativo na mortalidade de ninfas de B. tabaci biótipo B.<br>Looking for alternative methods of control to silverleaf whitefly Bemisia tabaci (Gennadius) biotype B in tomato, attractiveness and oviposition preference tests were accomplished in greenhouse using fourteen aqueous extracts at 3% (weight/volume). The extracts were prepared with parts from Azadirachta indica,Trichilia pallida,Chenopodium ambrosioides,Piper nigrum,Melia azedarach,Ruta graveolens,Ricinus communis,Mentha pulegium,Tagetes erecta,Eucalyptus citriodora, Cymbopogon nardus and Coriandrum sativum. The most efficient extracts in greenhouse were also tested in laboratory to evaluate the possible systemic effect on whitefly nymphs. Tomato plants sprayed with extracts of leaves from M. pulegium, leaves and seeds from A. indica were less attractive to the adults of the insect. Plants sprayed with extracts of leaves from A. indica and leaves + branches from R. communis showed deterrent effects on the insect oviposition, reducing the number of eggs; in an opposite way, the extract of leaves from C. nardus stimulated the whitefly oviposition on the plants. The use of extracts in a systemic way did not affect the whitefly development period (egg-adult). The extracts of seeds and leaves from A. indica and leaves from M. pulegium increased the mortality of nymphs of B. tabaci biotype B

Atratividade e preferência para oviposição de Trialeurodes vaporariorum em genótipos de aboboreira Attractiveness and oviposition preference of Trialeurodes vaporariorum in squash genotypes

O comportamento de 13 genótipos de aboboreira foi avaliado em relação à atratividade para adultos e à preferência para oviposição da mosca-branca Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae) em testes com e sem chance de escolha, em campo e em casa de vegetação. Os experimentos foram conduzidos com plantas de aboboreira em fase vegetativa, infestadas naturalmente no campo (atratividade para adultos e oviposição com chance de escolha) e artificialmente em casa de vegetação (oviposição sem chance de escolha). Dentre as aboboreiras tipo moita, o híbrido Arlika apresentou a menor atratividade para adultos e, entre os genótipos de crescimento rasteiro, não houve diferença em relação à atratividade. Quanto à preferência para oviposição em teste de livre escolha, 'Arlika', no grupo de moita, e 'Atlas', 'Sandy', 'Bárbara', 'Baianinha' e 'Caravela', no grupo das rasteiras, apresentaram os menores índices de oviposição, que se confirmaram no teste sem chance de escolha, indicando que a menor preferência para oviposição de T. vaporariorum nesses genótipos é estável.<br>Thirteen squash genotypes were evaluated in relation to attractiveness and oviposition preference of Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae) under field and greenhouse conditions. In the field, two experiments were carried out, one being with bush squash and the other with summer squash genotypes. Plant infestation occurs naturally after seedling transplanting. By counting adults on the abaxial surfaces of the leaves, in the bush squash experiment, the hybrid 'Arlika' showed the lowest attractiveness; in the summer squash experiment, no difference was observed among genotypes. Regarding eggs counting, 'Arlika' (bush squash experiment), 'Atlas', 'Sandy', 'Barbara', 'Baianinha' and 'Caravela' (summer squash experiment) presented nonpreference for oviposition. Oviposition was also evaluated in two no-choice experiments, with artificial infestation, under greenhouse conditions. In both, the least preferred genotypes for oviposition in the free-choice test maintained the nonpreference, demonstrating that the resistance is stable